The invention addresses in particular the case of containers consisting of a carboy of liquid, capable of containing at least about ten liters of liquid, notably water, typically water carboys of three, four or five gallons, which are used in the upside down position in dispensing fountains. The neck of these carboys is closed by a plug generally described as a <<snapped-on>> plug, i.e. a plug for which the tubular skirt is able to be interiorly clipped or more generally coaxially blocked around the neck, unlike screwed plugs for example. An example of such a plug is provided by WO-A-2004108584 on which the preamble of appended claim 1 is based. Most carboys of this type are reusable many times, by getting rid of their plug and then cleaned before each filling.
For various reasons, notably economic and ecological reasons, the carboys historically used, made in polycarbonate, are today increasingly replaced frequently with carboys in less rigid plastics, notably in polyethylene terephthalate. The result of this is that during the operation for plugging such a carboy after the latter has been filled, the setting into place of the plug by force on the neck causes a non-negligible elastic deformation of the whole carboy, which is thus crushed along the axis of its neck: the liquid level in the carboy is then raised relatively to the carboy so that it is frequent that a little liquid flows out of the carboy, by passing over the tree and of the neck, and then by flowing exteriorly around this neck, and this, at the moment when the plug is fixed around this free end. Under these conditions, liquid is found trapped in a substantially leakproof way between the outside of the neck and the skirt of the plug, this skirt being actually designed for snugly encircling the neck. Subsequently, the presence of this thereby trapped liquid is often perceived, moreover wrongly by the user as a lack of seal of the obturation of the neck. The presence of the capped liquid is moreover particularly visible when the carboy is, after filling and obturation, laid horizontally for purposes of storage and/or transport. Moreover, in the long run, this stagnant liquid between the outside of the neck and the inside of the skirt of the plug may be a source of hygiene issues, such as bacterial contamination.
The object of the present invention is to improve the plugs of the type mentioned above, in order to avoid the presence of liquid between the outside of the neck and the inside of the skirt after placement of the plug on the neck.